YES.
I have felt guilt for buying one cel that I 
have.  

When I first started the hobby back up early last 
year, I had a personal max of 500$.  Back then, 
500 would get you almost anything FY, it was 
considered a really high amt.  Now though...that 
amt isnt even enough for most nice cels of any of 
the main characters.  When I first started up, I 
went through my "young and stupid" phase.  I 
bought up alot of stuff for very high amounts.  
Come on, you guys remember...-_-  I wanted so 
much to be a part of the cool gang and the big 
spenders and have neat stuff to show.  
But...thank the gods...I have seen the err of my 
ways and have gotten much much better.  Going a 
grand into debt changed the hell out of me..  
Now, I only buy cels that I feel I absolutely 
will not sell.  The last sale run that Ive had is 
it...I went through last week and decided that 
what I have left I just like too much.

Anyways, onto the regret.  My one cel that I dont 
know if I will ever enjoy 100% is my profile 
death Nuriko cel.  I had to pay quite a load for 
it, I even had some help with it.  But, Im really 
not a fan of profile shots.  To pay what I did 
for a profile shot, I felt was a little crazy.  
On the other hand though, it is a cel of which I 
have only seen one with the eyes open...mine.  
All the others are eyes closed.  Also it's a rare 
scene, very pivotal in the series.  Cels from 
that part of the show are almost impossible to 
get, and when they do appear, they go for a lot.  
Just a couple weeks ago a cel like mine with eyes 
closed went for 400$ or so.  When I got the cel 
in, it was indeed an awesome cel though.  I love 
it very much....but I still have a tiny ounce 
of "God this cost me so much" rining in the back 
of my mind. And I know now that IF I resold 
it...Id never be able to get my money back. 

As I've gotten more wise in my collecting...my 
personal max has also grown....by leaps and 
bounds.  Now my personal max has 4 digits.  BUT, 
Im also a LOT pickier. There are only about 3 
cels I can think of that Id pay that much for, 
and I just got one of them.  The cel from Leigh 
that I won was in that 4 digit range...but there 
is NO regret.  I dont mind paying the big bucks 
for something truly worth it.  Just make sure you 
think so too.  If anything, this is a learning 
experience for you.  It will help you be a better 
judge in the future, and to not make anymore 
mistakes ^_~.  After some time, you'll forget 
what you paid for the cel anyways, then you can 
enjoy it.  I do that all the time.